7
Operating modes
Festo – GDCP-CMMP-M3/-M0-C-CO-EN – 1510b – English
191
setpoint_acknowledge
new_acknowledge
data_valid
2
1
3
4
5
6
7
Fig. 7.4
Positioning job transmission from a host
In Fig. 7.4, you can see how the host and the motor controller communicate with each other via the
CAN bus:
First, the positioning data (target position, travel speed, end speed and acceleration) are transmitted to
the motor controller. When the positioning data set has been completely written
1
, the host can start
positioning by setting the bit new_set_point in the controlword to “1”
2
. After the motor controller
recognises the new data and takes it over into its buffer, it reports this to the host by setting the bit
set_point_acknowledge in the statusword
3
.
Then the host can start to write a new positioning data set into the motor controller
4
and delete again
the bit new_set_point
5
. Only when the motor controller can accept a new positioning job
6
does it
signal this through a “0” in the set_point_acknowledge bit. Before this, no new positioning may be
started by the host
7
.
In Fig. 7.5, a new positioning task is only started after the previous one has been completely finished.
To determine this, the host evaluates the bit target_reached in the object statusword.
Time
t
0
v
2
v
1
t
1
t
2
t
3
Velocity
Fig. 7.5
Simple positioning task
